Condensation Causes Black Mould
We all do things on a daily basis that create water vapour. We cook, shower and dry wet clothes to name just a few. The creation of water vapour coupled with poor ventilation causes condensation. The water vapour condenses into water droplets on all your surfaces rather than being ventilated out of the house. Condensation is by far the biggest cause of black mould growth in homes across the UK.
If water vapour comes into contact with a cold surface (like an uninsulated wall or ceiling or a cold window) which is below the dew point it will form condensation - water droplets on a surface instead of a mist. If the condensation is not dealt with it will soak into all organic materials causing them to become damp. It's then just a matter of time until mould begins to grow.
What is Dew Point?
The Met Office defines dewpoint as follows:
The temperature at which condensation occurs is called the Dew point and is dependent upon the humidity and pressure of the air.
Dew point is the temperature at which condensation occurs. Or, in other words, the temperature at which water vapour forms into water droplets on your surfaces. This is key. Mould feeds on moisture and needs it to grow. Dew point is the key to understanding if you're creating condensation in your home. When your home has reached dew point, it means the environment has now become one in which water begins to condense on your surfaces. In other words - mould food.
However, it's not as simple as keeping your home above a certain temperature to avoid condensation and mould. There are three variables that affect condensation: temperature, air pressure and humidity.
If you understand the dew point of your home, you know when to either turn the heating on or open some windows and turn on extractor fans. How can you ensure your home doesn't reach dew point? We'll go through some examples, assuming air pressure is constant as this is more difficult to manipulate.